When a cop is shot it is very personal for the local police force. So when a mississippi officer was killed and another critically wounded before christmas, more than 100 members of law enforcement worked through the holiday with one major clue. Surveillance video. And tonight, a break in the case. Here is abc's ron claiborne. &#9834; Reporter: It was supposed to be a night of peace, but for the people of tupalo, mississippi, christmas has turned into a season of sorrow. &#9834; it started with a bank robbery monday, and it ended with a police officer gunned down, his partner critically wounded. Authorities launching a nationwide manhunt, the fbi tracking down leads from as far away as chicago. They're looking for this man, captured on surveillance camera at 3:15 p.M. Police say as he was about to rob a bank. His face mask in his hand, a gun. A short while later the bank robber possibly with one or more acompolices gunned down the officer and wounded another officer as the robber's car was stopped at a railroad crossing. Tonight the fbi announce they'd believe the same gunman commit aid robbery in atlanta, georgia, nearly 300 miles away earlier that same day. Investigators here in atlanta, the fbi, atlanta police were working hard to try to find out why he was in atlanta and more importantly who he is. Reporter: These surveillance videos from 9:30 show a lone gunman wearing a black ski mask armed with a semiautomatic handgun demanding money from the tell ter. When that failed he rushed out of the atlanta bank, stopping to rob a skus myrrh taking money out of an atm machine. Meanwhile back in mississippi, law enforcement officials welcome the broadening investigation. We have provided media with a wanted poster, providing information and surveillance photos from the atlanta bank robbery which provide a clearer picture of the robber. Reporter: Earlier this week, police released a photo of this man, calling him an of interest in the robbery there. Taken by a convenience store security camera just prior to the bank robbery. Yet another video shows what police say was the robber's car speeding away from the bank's parking lot. In tupalo, the joy of the christmas season replaced by mourning for an officer lost in the line of duty. I am at peace with gale. I know he died doing what he loved. Reporter: The officer was laid to rest today. Another man lost too young, doing his duty, protecting his town and city. Reporter: The reward has grown to $200,000 for information leading to the arrest of the officer's killer or killers. Meanwhile the wounded policeman, he is getting better, slowly. His condition improving from critical to serious. The following is a paid advertisement

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